foo.go

package main

import (
	"encoding/json"
	"fmt"
	"math/rand"
)

type T struct {
	Value int64
}

func main() {
	var foo T

	foo.Value = rand.Int63()

	data, err := json.Marshal(foo)
	if err != nil {
		fmt.Printf("err1:%v\n", err)
		return
	}

	var bar map[string]any
	if err := json.Unmarshal(data, &bar); err != nil {
		fmt.Printf("err2:%v\n", err)
		return
	}

	data2, err := json.Marshal(bar)
	if err != nil {
		fmt.Printf("err3:%v\n", err)
		return
	}

	var baz T
	if err := json.Unmarshal(data2, &baz); err != nil {
		fmt.Printf("err4:%v\n", err)
		return
	}

	fmt.Printf("foo.Value = %d, bar.Value = %v, baz.Value = %d, %v\n", foo.Value, bar["Value"], baz.Value, foo.Value == baz.Value)
}

12:33:26 0 jfelice@C02FV0KUQ05Q nexus (jf-in-545)
ᐅ go run /tmp/foo.go
foo.Value = 403136368954160975, bar.Value = 4.0313636895416096e+17, baz.Value = 403136368954160960, false