Means testing after ESA migration to UC?

I gave AI my recent ESA award breakdown as I’m migrating to UC and wondered where that left me re any potential future savings. I get the Christmas bonus which I understand is only paid to people receiving contributory benefits

AI reckons:
Current ESA Award Breakdown
Weekly payment of £161.75 is composed of:

Contribution-based ESA: £92.05 (living expenses) - NOT means-tested

Income-related ESA: £69.70 total, consisting of:
a. Disability Income Guarantee: £21.20 - IS means-tested
b. Support Group addition: £48.50 - IS means-tested

During your Universal Credit migration, your mixed ESA award will be split into two separate benefit streams:
1. Income-related portion (£69.70) → Ends and becomes part of Universal Credit
2. Contribution-based portion (£92.05) → Automatically converts to New Style ESA
Automatic Conversion to New Style ESA
Your contribution-based ESA will automatically convert to New Style ESA without requiring a new assessment. Since you’re in the Support Group, your New Style ESA will be:
• Weekly amount: £140.55 (Support Group rate)
• Fortnightly payments: £281.10
• Payment frequency: Every two weeks
• Means testing: NOT means-tested

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I know AI often gets stuff wrong so wonder if it’s done a good job in this case?

Lets say notionally my future savings go to £20k. Where would that leave me after migration?

Oh, sorry, I thought it was a straight UC migration query

Not to put too fine a point on it, I might get some money when my mum dies and I’m wondering how this would affect me given my mixed contributory/means tested benefits components. Is that not something this forum can be used for? Advice on entitlement and rules?