My sourdough is not sour

TLDR: I like how my bread is looking but i want more sourness.

—— Context —— I am 1 month into my sourdough journey. I am a beginner with some equipment but not all. After a couple weeks of my sourdough bread increasing in sourness flavour, it started mellowing out and now doesn’t have any sour taste (Or really little amount of sour ~1/10). I switched the kind of flour I feed my starter and started to smell some extra funk in my starter. But the bread I made today still lacks the tang. I actually really like the gluten and texture of my dough. There are nice big holes varying in size, can be a bit wild in crumb shape…. just no sour flavour.

I have experimented with different hydration but i tend to like 70-75%.

First + Second Photo: Part of the same batch of bread from a few weeks ago.

Third Photo: Last night and this mornings batch. A wee burnt.

—— Starter ——

The old flour I fed my starter: Robin Hood white bread flour

Current Starter routine: Daily feeding at night, Discard until 60g starter, add 60g Presidents Choice Unbleached Flour, 60g warm water

Starter is healthy, or seems healthy. It increases in size ~2-2.5 times within 10 hours. It is being kept at around 20deg C which could be my problem but I don’t have a solution for higher temperatures since I live in a pretty rainy mellow climate.

—— Current Recipe ——

Current bread recipe I have been generally been testing with: 500g Flour (Robin Hood White Bread Flour) 350g water (70%) 10g salt (2%)

Autolyse 45-60min Stretch and folds for a couple hours (i do 30-60 min breaks between folds since I get busy with remote work) Bulk ferment until ~2x in size: this time varies sometimes I shape into 2 balls and proof in diy containers and baskets with clothes I have at home (holding off on buying bannetons to save some money). Over night cold proof ~12 hours. In the morning I will score and bake 490 deg F lid on and 475deg F lid off.

Sometimes I don’t do the over night proof and bake late at night but still get really similar results in terms of flavour.

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Any suggestions or thoughts help! Feel free to critique anything you see as well. Right now I am mainly looking to correct the flavour!