Tithing is in the Bible, but the New Testament never commands Christians to give exactly 10%. The tithe was part of the Old Testament law for Israel (Leviticus 27, Numbers 18, Deuteronomy 14). If you add up every tithe Israel was required to give, it was closer to 20-23% than a flat 10. The idea of giving exactly a tenth of your income comes from church tradition.
2 Corinthians 9 talks about giving generously and cheerfully. My spouse and I treat 10% as a starting point, and some seasons we’ve given more, some less. Since you’ve been on autopilot, pray about what giving should look like in your situation rather than treating it as tax.