ASX Today, page-557

It's hard to tell from the patent application description whether or not Alexium PCM is used.

The patent application WO2019036559 Serrata Simmons Bedding claims to be agnostic as to the PCM:

[0025] The particular PCM is not intended to be limited and can be inorganic or organic. Suitable inorganic PCMs include salt hydrates made from natural salts with water. The chemical composition of the salts is varied in the mixture to achieve required phase-change temperature. Special nucleating agents can be added to the mixture to minimize phase-change salt separation. Suitable organic PCMs include fatty acids, waxes (e.g., paraffins) or the like.

There is no reference to Alexium PCMs in the description or claims.

The prior art cited in the International Search report does not include any Alexium patents.

The essence of the invention seems to be the use of a layer of tangled fibres coated with microencapsulated PCM to improve air flow to remove heat from the PCM. Otherwise it would just delay heating.

None of which proves that they are not using Alexium, so fingers crossed.