Questions about Seagate IronWolf Pro High WRL

Of course. But I don't know what effect this has on RAIDs, whether the slower speed is then simply used for all disks. But if you either don't have a RAID or only combine discs of the same speed in a RAID, it's not a problem.

I have no error message HD works ok for me in my Synology NAS

It works. I am using it with Synology. The main reason is likely the noise level, and energy consumption if you have a very large NAS: enterprise HDD are designed for different specs, and NAS-specific drives have special features to make them quiet. In this specific case, it can take a while to spin up all the drives if they sleep and when they are working they are noticeable louder than my precious NAS-specific Ironwolfs