Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: 1.70
• OS Version: Browser (Firefox, maybe Chrome)

Steps to Reproduce: Not sure.

Reported originally in Gitpod:

• Terminal character display issue in firefox gitpod-io/gitpod#8935
• Black blocks in terminal at every underscore gitpod-io/gitpod#12190
• Underscore shows incorrectly in Terminal gitpod-io/gitpod#12145