Storm in a Tea Cup?

Tesco's Finest Green Tea and Jasmine pyramid tea bags are sold as 'biodegradable'. These teabags are fashioned, using a plant-based bioplastic, polylactic acid. Cork University researchers have tried burying these teabags in the garden. The teabags showed no hint of breaking down, after up to one year in the soil (https://www.theguardian.com/environment/2023/feb/28/tesco-accused-of-greenwashing-over-biodegradable-teabags). The Cork University group suggest that Tesco are 'greenwashing' their teabags. They think the teabags could more fairly be described as 'plant-based' or 'compostable', rather than 'biodegradable'. Tesco have retaliated. They point out that their packaging, advises customers to dispose of used teabags with the local council's food waste. Customers are not encouraged to place the teabags in home compost bins. This is not what most people would understand by use of the term 'biodegradable'. A touch of 'greenwash' here?