Summoner's spell 'Egi Assault' does not correctly affected by the spell speed

As the title is shown, Summoner's spell 'Egi Assault' does not correctly affect by the spell speed

I have an lv78 summoner with 926 spell speed
Under these properties, most of the regular GCD is 2.44s, for example, spell 'Ruin II'

but the 'Egi Assault' charge time still at the 30s, as it belongs to the spell, it should at 30*2.44/2.50 = 29.28s

It is correctly prestences at 29.28s before patch 5.4
And I did not find any patch note for modification summoner spell 'Egi Assault' in patch 5.4, 5.41, 5.45 and 5.5, but it changed, so I think it is a BUG


Date & Time: 30/04/2021
Frequency: permanent after patch 5.4
World name: Tonberry
Character name: Maid Misa-erika
Retainer name: N/A
NPC name: N/A
Monster name: N/A
Class/Level: Lv78 Summoner
Party or solo: solo
In-game time: permanent after patch 5.4
Area and coordinates: anytime
Housing: N/A
Steps:
1. lv78 summoner with 926 spell speed
2. Most of the regular GCD is 2.44s, for example, spell 'Ruin II'
3. But the 'Egi Assault' charge time still at the 30s, as it belongs to the spell, it should at 30*2.44/2.50 = 29.28s

Read the tool tip

"This action does not share a recast timer with any other action. Furthermore, the recast time cannot be affected by other actions."