Photoshop inserts “5” while replacing text and changes layer opacity to 50%

Photoshop version: 27.11.0
Operating system: macOS Tahoe 26.6.1
Hardware: Apple M4 Pro

Steps to reproduce:
1. Open a Photoshop document with multiple text layers.
2. Copy text from one text layer.
3. Open another text layer and select its text for replacement.
4. Paste the copied text and continue editing.
5. Perform another operation or click elsewhere.

Actual result:
The number “5” is sometimes inserted into the text even though I am not pressing the 5 key. At the same time, the selected layer’s opacity changes to 50%.

This happens frequently during text replacement. The key I press is physically far from the 5 key, so this does not appear to be accidental key input. It seems that the text input may be interpreted as a global Photoshop shortcut as well.

Expected result:
Only the intended text should be pasted or edited, and the layer opacity should remain unchanged.