What does Apple mean by "redeem by"

When Apple says an offer "Must be redeemed by" a certain date do they mean it has to be redeemed before that date or can it be redeemed on that date. I tried activating an offer for 6 months of Apple TV that said "Must be redeemed by July 31, 2023" on July 31, 2023. When Apple defaulted me to the 1-week trial rather than the 6-month promo, I was told by Apple support that the reason I didn't get the promotional offer was because I needed to redeem the offer before July 31st, but this seems nonsensical to me.