As an owner of a MSFFB2 (the silver trigger/green power light version of the MSFFB2, if that matters) this input delay issue has plagued me since I got the module over a year ago and has severely impacted my ability to use it. I haven't taken the poor gal out of the hanger for more than a handful of flights. I can also confirm it only exists on the F-14 module and none of my other modules, some of which have also developed their own FFB effects.
For reference, my DCS is the steam version and this input lag issue has been apparent on both my old system, and my completely new system. Neither of my systems have shared any hardware or DCS configs. Everything is new and different, from monitors to keyboard and mouse. The only similarity has been the MSFFB2 joystick. Also, not that it matters all that much, but my old system was an Intel i5-4670K & Nvidia 2070 Super, and my new system is an AMD 3900X & Nvidia 3080.
Anyway, Aries, I may have a semi-fix you could try out: In your autoexec.cfg, paste this and let me know if it makes any difference to the input lag:
input = { threaded_ffb = false }
While the above removed the severe input lag on the F-14, I unfortunately still couldn't stomach the insane FPS hit I'd get when any force feedback was in effect for this module. For example: I could be in a free flight with no other entities but the F-14, and I could be getting a stable 120fps, but the moment I pulled enough G's to trigger the rumble force feedback effect for example, I'd drop to ~50fps or so for as long as that effect was active. If I were to turn off force feedback in the settings and do the same test, my frames wouldn't budge from 120fps during the high G effect.
While on a monitor I'd find this acceptable-ish, I unfortunately only really fly in VR these days and with DCS being a tad unoptimised in VR, the performance hit is unplayable and pretty much headache inducing.