They offer a "JetBrains Mono NL" variant where the NL is for No-Ligatures. I use it daily on Eclipse.
I wasn't aware that you could disable them, I thought this was handled entirely by the font and not by the editor. Living and learning. Might try JetBrains Mono again without ligatures this time, after I finish my trial of IBM Plex.
Ah, no, I phrased that in a rather callous way. I'm sorry – my apologies.
If you do decide to give it a try, I hope your editor makes it easy to configure (since they really run the gamut) and that you have another typeface to enjoy!