Mutations need to run Synchronous

Do your async work in action rather than mutation

Not the best implementation, but you will get an idea how to approach it from the code below.

//mutations.js
    SET_API_ENDPOINT(state, payload) {
      // Clear the previous interval to prevent a memory leak
      if (state.api.interval !== null) {
        state.api.interval = null
        state.api.data = {}
      }
    
      // Reset the API parameters
      state.api.endpoint = payload.endpoint
      state.api.requestType = payload.requestType
      state.api.payload = payload.payload
      state.api.interval = payload.interval
      state.api.data = payload.data
    }




 //actions.js:
        async setAPIEndpoint({ commit, state }, payload) {
        
          const endpoint = payload.endpoint;
          const requestType = payload.requestType;
          const payload = payload.payload;
          let data = null;
          let interval = null;
          const getData = () => {
            return new Promise((resolve, reject) => {
        
              interval = setInterval(() => {
                if (requestType === 'post') {
                  axios.post(`/api/${endpoint}`, payload)
                    .then((response) => {
                      data = response.data;
                      resolve();
                    })
                    .catch((error) => {
                      process.env.NODE_ENV === 'production' ? location.href = 'pages/error-500/' : console.log(error)
                      reject();
                    })
                }
              }
                , state.api.refreshTimer);
            })
          };
        
          await getData();
          const newPayload = {
            ...payload,
            data,
            interval
          }
    
      commit('SET_API_ENDPOINT', newPayload)
    }

This answer is based on @Abdullah Khan's. Refer to it for additional context.

Below is an implementable solution for anyone landing here from Google with a similar use case.

In your Vue component which need to update the API, call below from a method / lifecycle hook:

await this.$store.dispatch('setAPI', {
    requestEndpoint: '/api/endpoint',
    requestType: 'get',
    requestPayload: {}
})

In actions.js:

import axios from '../axios'

const actions = {
    clearAPI ({ commit }) {
        commit('CLEAR_API')
    },
    async setAPI ({ commit, state }, payload) {
        commit('CLEAR_API')

        const requestEndpoint = payload.requestEndpoint
        const requestType = payload.requestType
        const requestPayload = payload.requestPayload
        let data = null

        const getData = () => {
            return new Promise((resolve, reject) => {
                if (requestType === 'get') {
                    axios.get(requestEndpoint, requestPayload)
                        .then((response) => {
                            data = response.data
                            const newPayload = {
                                requestEndpoint,
                                requestType,
                                requestPayload,
                                data
                            }
                            commit('SET_API_DATA', newPayload)
                            resolve()
                        })
                        .catch((error) => {
                            process.env.NODE_ENV === 'production' ? location.href = 'pages/error-500/' : console.log(error)
                            reject()
                        })
                }
            })
        }
        await getData()

        const interval = setInterval(() => { getData() }, state.api.pollTimer)
        commit('SET_API_INTERVAL', interval)
    }
}

In mutations.js:

const mutations = {
    CLEAR_API (state) {
        // If interval exists, clear it
        if (state.api.interval) {
            clearInterval(state.api.interval)
        }

        // Clear the API parameters
        state.api.requestEndpoint = null
        state.api.requestType = null
        state.api.requestPayload = null
        state.api.data = {}
    },
    SET_API_DATA (state, payload) {
        // Set the API parameters
        state.api.requestEndpoint = payload.requestEndpoint
        state.api.requestType = payload.requestType
        state.api.requestPayload = payload.requestPayload
        state.api.data = payload.data
    },
    SET_API_INTERVAL (state, interval) {
        // If interval exists, clear it
        if (state.api.interval) {
            clearInterval(state.api.interval)
        }
        // Set the API Interval
        state.api.interval = interval
    }
}

In state.js:

const state = {
    api: {
        requestEndpoint: null,
        requestType: null,
        requestPayload: null,
        data: {},
        interval: null,
        pollTimer: 5000 // Milli-seconds
    },
}