Steps to reproduce:
- Select any lens except "Discussions"
- Flip the switch next to your currently active lens
- Note that your lens' name is still next to the switch
- Flip the switch again
- Now the active lens is "Discussions"...
It would re-activate the last used lens
Opera GX on Windows 10
United States Region - US-WEST server
Notice that the previous lens' name shows up next to the switch, so you expect that lens to activate when you flip the switch: