Well if you are ever bored and want to visit my world, I will show you the crazy spawns on my cleared, muddy, flattened beach. You will see things spawn before your very eyes.

The link you are unwilling to click is a link to a Valheim wiki page that lists structures that provide "player base" of 20 meters around them (any area designated 'playerbase' will prohibit spawns).

Copy and pasted for your information:

The following structures have 20 meters of player base around them:

Artisan table
Bed
Blast furnace
Bonfire
Campfire
Charcoal kiln
Dragon bed
Fermenter
Forge
Hanging brazier
Hearth
Portal
Sconce
Smelter
Spinning wheel
Standing green-burning iron torch
Standing iron torch
Standing wood torch
Stonecutter
Ward
Windmill
Workbench

Source: https://valheim.fandom.com/wiki/Player_base

So could it be possible that one of these structures were near your cleared area that might have reduced spawn in your cleared area giving you the impression it was because of the cleared area?

Just a thought.