Microsoft recommend to use GMSA account as service account instead of standard user because it's more secure.
In the following link you will find the benefits of GMSA: Benefits of using gMSAs
Regarding SPN configuration ,you also can add SPNs on GMSA account.
May be you will have a downtime to switch to GMSA , but you will have also a downtime to reset the password of standard user service account.
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