Stratis is not a traditional fs. It's implemented as a user-space daemon that communicates with lvm, devicemapper, and xfs in the background to do its magic. So you need indicate that the mountpoint should wait for that daemon to start before attempting to mount. You want to add the x-systemd.after=stratisd.service mount option for that.

For example: UUID=a1f0b64a-4ebb-4d4e-9543-b1d79f600283 /fs1 xfs defaults,x-systemd.requires=stratisd.service 0 0

More here: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_file_systems/managing-layered-local-storage-with-stratis_managing-file-systems#persistently-mounting-a-stratis-file-system_setting-up-stratis-file-systems