Dear Hesham,
Armour designers and gun designers are allows leap-frogging each others; latest invention.
For example, during World War 1, machine guns killed millions of infantrymen, so Britain invented armoured tanks to cross open ground raked by machinegun fire, then Germany invented the first Anti-tank gun, a huge Mauser bolt-action rifle.
As thicker armour was developed during the inter-war period, anti-tank guns grew to 20 mm ... too heavy for a single man to carry.
Gunners responded by developing anti-tank rockets (Panzerfaust and Bazooka).
The next generation of tanks got thicker armour and spaced armour (track skirts and lockers around the turret).
Then gunners invented guided anti-tank missiles with better range and accuracy.
Then British tankers introduced Chobham composite armour.
The gunners added double explosive warheads to their anti-tank missiles (e.g. later versions of Russian RPG).
Then Russian tankers added explosive armour.
Then Sweden introduced Bill, top-attack missiles.
Then some one invented active, radar guided anti-anti-tank missile systems that try to intercept incoming missiles with rapid, out-going fire.
And the cycle resumes ......
At best, gunners are one step ahead of armourers. The best anti-tank weapons of 2021 is only effective against tanks built before 2021, because 2022 tanks will get updated armour.