That's not what the SAFE says. It's only on subsequent securities, not prior ones.
"If the Company issues any Subsequent Convertible Securities with terms more favorable than those of this Safe (including, without limitation, a valuation cap and/or discount) prior to termination of this Safe, the Company will promptly provide the Investor with written notice thereof, together with a copy of such Subsequent Convertible Securities (the “MFN Notice”) and, upon written request of the Investor, any additional information related to such Subsequent Convertible Securities as may be reasonably requested by the Investor."
"If the Company issues any Subsequent Convertible Securities with terms more favorable than those of this Safe (including, without limitation, a valuation cap and/or discount) prior to termination of this Safe, the Company will promptly provide the Investor with written notice thereof, together with a copy of such Subsequent Convertible Securities (the “MFN Notice”) and, upon written request of the Investor, any additional information related to such Subsequent Convertible Securities as may be reasonably requested by the Investor."
https://www.ycombinator.com/documents/