For 2024, the lifetime exemption is $13.61 million.
If you hit that limit this year, then when the exemption drops you would clearly be done and any further gifts that exceeded the annual exclusion would be subject to being taxed.
If you gave $8 million this year (and that was your lifetime total), then you would also be done if the exemption dropped below that figure in the future. However, note that if the exemption dropped to $6 million, the IRS will not try to claw back the $2 million (i.e., $8 million minus $6 million) and they have already made that point clear.
