Having a mental block with this one. At first it seems straight forward, but the last part of the wording confuses me.
BOA has a BT offer for up to one year at 0% APR, but with a 3% transfer fee (by Feb 9). OK, good so far.
Here's the wording : "..Transaction Fee: 3% of each transaction. Effective Feb 24, 2024, 4% of each transaction, unless you contact us to reject by Feb 23, 2024..." At first I thought it meant that after Feb. 24, if I made a BT it would be 4%. But that can't be the case. If so, they wouldn't have said I intially I had to make the BT by Feb. 9th. What exactly do they mean here? 
I would understand it as your 0% offer is good until 02/09 (with 3% fee).
between 02/10-02/23, the apr is expired (probs standard apr) but the fee is still 3%.
on 02/24, the standard fee is 4%, regardless of promo offer or standard apr.
if you contact "to reject," what are they going to do, keep it at 3% or stop offering balance transfers?
@Curious_George2 wrote:You are overthinking it.
They are making an across-the-board increase in the BT fees they charge, so they are disclosing that repeatedly, in many different places, using boilerplate language.
If you do a BT before your specific offer expires on 2/9, your fee will be 3%.
Thanks @Curious_George2 