You need to introduce multiple cards that can interact with triggers that occur when a land enters the battlefield already. This has gotten out of hand and is proving to be a greedier monster that needs some kind of response. You let blue counter players all day and stax prevent players from playing. This doesn't interfere with actually playing lands, it just stops the secondary value engines from overproducing.

The 2–3 Mana Cheap Techs (The "Safety Valves")

• Artifact / Enchantment ({2} or {1}{W}): "Lands entering the battlefield don't cause abilities to trigger."

The 4–5 Mana Mid-Tier (The "Value Stax")

• Enchantment ({2}{W}{U} or {3}{G/W}): "Lands entering the battlefield under an opponent's control don't cause abilities to trigger. Whenever a land enters the battlefield under your control, you gain 2 life and scry 1."

The 6 Mana Mythic (The "Uno Reverse Card")

• Artifact / Legendary Enchantment ({4}{U}{B} or {3}{W}{U}{B}): "If a land entering the battlefield under an opponent's control would cause an ability of a permanent they control to trigger, that ability triggers under your control. You may choose new targets for it."

It targets the exploitative mechanic, leaves the basic mana system intact.