SG should connect to 2 switches with multiple VLANs without stack / LACP

Hello;
does someone with the following construct have good or bad experiences?
Two switches (without stack functionality) are to be interconnected via the UTM.
Both switches have the same layer2 networks (multiple VLANs). The switches are also directly connected.
Is it possible to realize this with bridge-group?
Recommendations regarding SpanningTree?
Some better ideas?

Background:
To the switches, servers are connected by means of adapter failover and these should continue to run in the required frequent switch updates.
This is not possible with a stack because all stack members go down

Thanks