Steps to reproduce:

Read the following string with eSpeak NG and NVDA 2021.1beta1:
Warning: Will cause broken English speech. This can be fixed by restarting NVDA or by changing the variant or language and then setting it to the previous setting.
ᎯℳℐℕᎯ

Actual behavior:

After reading the string (or other strings like it), eSpeak NG attempts to read English in a strange, unintelligible accent. This can be fixed by restarting NVDA or by changing the variant or language and then setting it to the previous setting.

Expected behavior:

NVDA should read the string (or strings like it), but should not try to speak other English words in a strange accent.

System configuration

NVDA installed/portable/running from source:

Installed

NVDA version:

2021.1beta1

Windows version:

Windows 10 Pro version 20H2

Name and version of other software in use when reproducing the issue:

N/A

Other information about your system:

eSpeak NG settings
Voice: English (America)
Variant: Nguyen
Rate: 40
Rate boost: checked
Pitch: 51 (caused by issue #9811/#11832)
Inflection: 51 (caused by issue #9811/#11832)
Volume: 100
Automatic language switching (when supported): unchecked
Automatic dialect switching (when supported): unchecked
Punctuation/symbol level: most
Trust voice's language when processing characters and symbols: Checked
Include Unicode Consortium data (including emoji) when processing characters and symbols: checked
Capital pitch change percentage: 50
Say cap before capitals: unchecked
Beep for capitals: unchecked
Use spelling functionality if supported: checked

Other questions

Does the issue still occur after restarting your computer?

Yes

Have you tried any other versions of NVDA? If so, please report their behaviors.

NVDA 2020.4 does not do this.

If add-ons are disabled, is your problem still occurring?

Yes

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

Yes