How to resize a partition when the empty space is behind the partition.

I had 2 partitions in my hard drive where I am using one of those for time machine backup. Now I need to resize the partition and for that I shrunk the main partition from 440 GB (macOS Big Sur HD) to 400 GB giving me 40 GB of free space (Untitled). But the issue is that I cannot simply increase the size of the Time machine partition because the free space is behind the partition.

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Need to increase 60GB Time machine partition to 100GB

I would prefer to not lose any backup unless that is the last option because I've been using this for months now.

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I've been getting these notifications lately.

Is there a way around this?