Important to note here that it's only possible to "fool" SafetyNet/Play Integrity because of compatibility with older devices. The strongest Play Integrity level (MEETS_STRONG_INTEGRITY) is simply not possible to fake on a device with an unlocked bootloader, it's just not a big problem right now because most apps do not require it yet, since there are still many old devices that don't pass it, because of missing hardware or outdated android versions.
Eventually, in a few years, a time will come where the number of non-unlocked devices not compatible with MEETS_STRONG_INTEGRITY will be low enough that apps will start requiring it, and that will be the end of bootloader unlocking for most users that still do it.