Notebookcheck:
X220t: https://www.notebookcheck.net/Review-Lenovo-ThinkPad-X220T-4298-2YG-Convertible-Notebook.60217.0.html
X230 (max 39-40dB(A)): https://www.notebookcheck.net/Lenovo-ThinkPad-X230-2306-2AU-Laptop-Review.75317.0.html
W520 (max 39-40dB(A)): https://www.notebookcheck.net/Review-Lenovo-ThinkPad-W520-Notebook.53220.0.html
Framework (max 47-48dB(A)): https://www.notebookcheck.net/Framework-Laptop-13-5-Review-If-Microsoft-Made-A-Repairable-Surface-Laptop-This-Would-Be-It.551850.0.html
Maybe time to re-paste those ThinkPads you have if you haven’t done so. (To make sure they’re still functioning in-specs)
Having said that, capability / speed of the CPU come into the picture: Framework being the newer / faster laptop, it can handle more processing in shorter time. i.e. Old systems will be under load for longer…and longer fan on time. But the older Thinkpads are incapable of being louder than the Framework laptop (their fans are not as loud).
Or maybe your hearing / ears are just less sensitive to the fan noise frequency from the Framework laptop (predisposition).