Your threadlift was done 4 weeks ago before your flight. I would be interested to know what thread was used. Was there any issue in between?
If not, it is more important that you visit your doctor to assess on the raised bump. Threadlift has not been a contraindication for long haul after it has healed.
And 4 weeks is usually more than enough time. Plus 10 cm wide is really big, and a proper assessment is recommended. It might be due to other reason. Take care and keep me in the loop of your outcome.
Regards,
Elias
