The fire particles that appear when a mob spawner is within range of a player can not be seen through stained glass but can be seen through normal glass.
MC-194577
Graphical glitch with mobspawners and stained glass
Resolved
Duplicate
0
Burning Sulphur
(Unassigned)
Unconfirmed
(Unassigned)
1.16.1
Retrieved
Duplicate of MC-189283 Though that report still needs what graphical settings it was on if you could help that report out by commenting what your graphis setting was on that would be greatly appreciated.