Greetings MattyMurda,
If you are unfamiliar with an icon in your Menu bar, you can look at the Activity Monitor to see what's running.
"In the Activity Monitor app on your Mac, do any of the following:
- To view processor activity over time, click CPU (or use the Touch Bar). The following percentages appear in the bottom of the Activity Monitor window:
- System: The percentage of CPU capability that’s being used by processes that belong to macOS.
- User: The percentage of CPU capability that’s being used by apps you opened, or by the processes opened by those apps.
- Idle: The percentage of CPU capability that’s not being used.
- To view current processor activity, choose Window > CPU Usage.
- To view recent processor activity, choose Window > CPU History.
- To display more columns, choose View > Columns, then choose the columns you want to show." View CPU activity in Activity Monitor on Mac - Apple Support
Also, be sure to restart your Mac if you are experiencing unexpected behaviors, as this can really help. Shut down or restart your Mac
We hope this helps!
Best wishes.