Holding Shift, the = key types a +
With Caps Lock on, the = key types an =
AFAIK, this is the only key that does this.
It only happens in LO, both in Writer and Calc.
Edit: Version: 220.127.116.11 (x64)
Version: 18.104.22.168 (x64)
Build ID: 0ce51a4fd21bff07a5c061082cc82c5ed232f115
CPU threads: 8; OS: Windows 10.0 Build 19041; UI render: default; VCL: win;
Locale: en-US (en_US); UI-Language: en-US