iOS 13 -- Text entered into various apps contains invisible unicode character ("Object Replacement Character")

This has been an issue since I installed the iOS 13 public beta and has not been fixed up through iOS 13.1.3.

In various apps, when I enter text using my phone, the text I have entered includes a unicode character that is invisible on my phone but apparent when I view the text on any Mac or PC. It occurs most commonly at places when I have double spaced to end with a period.

The character is the "Object replacement character", or . (if you're not seeing it here, I guess you're probably on mobile, but it looks like an "OBJ" inside a dotted line box.)

I first noticed it happening from a reddit app, so I switched reddit apps and it still occurred. Then I logged into reddit on the Firefox app and typed a comment with that and got the same thing. It has happened with non-reddit text entry but I can't remember specifically where else I've seen it. Anyway, it seems like an iOS issue, and not a problem with a specific app or website.

Any thoughts on what might be causing this, or how to fix it? Thank you!