Are you playing on a phone or using a high DPI monitor? By default HTMLcanvas (which most game engines use to handle text) does not take into account high DPI scaling (I would guess due to performance).

This isn't inherit to JS game engines, but I will say text quality is not usually something that game devs focus on unless text is important to their particular game.

Here's an example of a workaround to render more crisp text https://github.com/danman113/gfx-utils/blob/main/src/canvas/...